An apparatus for dispensing predetermined amounts of lining material in cap shells has been utilized in the past. For example in Japanese Patent Application Publication 42-20759 (1967) an apparatus is disclosed for distributing a predetermined amount of lining material in cap shells where the apparatus has a shell transport means for moving a cap shell through the machine along a path at a predetermined speed. A lining material extrusion means is positioned along and above the path of movement of the shell through the machine where the extrusion means extrudes a predetermined amount of lining material through an extrusion passage and where a rotatable cutting knife is positioned adjacent the exit end of the passage for cutting across the lining material as it is forced from the passage and for moving the material into the shell. A driving apparatus for rotating the knife is timed with relation to the transport means for moving the cap shell through the machine.
It is difficult, however, in a machine following the construction that application to distribute predetermined amounts of lining material into a cap shell having a deep depth or a long skirt. This is because the cutting knife rotates at a constant speed with respect to movement of the shell through the machine with the result that the outer radial edge of the knife strikes against the skirt of the cap shell resulting in unsatisfactory operation.
It has been proposed to overcome the deficiency outlined above by providing a machine which has means for driving the cutting knife at varying rotational speeds. Such a machine is disclosed in my prior U.S. Pat. No. 4,060,053 wherein a means is provided for varying the rotational speed of the knife with respect to the speed of movement of a cap shell such that the radial edge of the cutting knife decelerates gradually as the cutting knife approaches the cap shell transport path and accelerates gradually as it departs from the shell transport path. Contact between the radial outer end of the cutting knife and the skirt of the cap shell is thus prevented even in cap shells having deep depths. Further the machine as disclosed in my prior patent is capable of substantially equalizing the speed of movement of the cap shell and the speed component of the radial outer tip of the knife in the direction of the path of movement of the shell through the apparatus at the instant the cutting knife deposits the lining material into a predetermined area on the inside bottom surface of the cap shell. The cutting knife then rotates upwardly and away from the predetermined area such that once the lining material has been deposited in the prescribed area, it will remain without danger of later movement by the cutting knife as the knife continues to rotate.
The driving means driving the cutting knife in the machine of my prior U.S. patent comprises an electric motor drive source that rotates at a predetermined speed and includes a transmission mechanism that transmits the output of the electric motor to the cutting knife while varying the speed of rotation of the cutting knife. As shown the transmission mechanism includes a pair of non-circular gears to provide the varying drive speed to the cutting knife. It is also possible to utilize a pair of eccentric gears, special ring mechanisms or cam mechanisms instead of non-circular gears. However when eccentric gears are used, it is difficult to maintain balance between the gears under high speed operation because of the eccentricity of the gears to the axis of rotation. Special ring and cam mechanisms are not satisfactory because of their high manufacturing costs.
When using non-circular gear pairs for converting constant speed rotation to variable speed rotation, the degree of speed conversion or variation achieved depends upon the degree of oblateness of the non-circular gears where the degree of oblateness of a gear is defined as .epsilon.=long diameter-short diameter/long diameter+short diameter.
As disclosed in my early patent, the required degree of conversion or variation of the rotational speed of the cutting knife that must be obtained depends upon the depth of the cap shell on which the lining material is to be distributed. This then requires that there be a set of non-circular gears available having a particular degree of oblateness for each cap shell of a particular depth.
Non-circular gears commercially available are limited to predetermined degrees of oblateness .epsilon. as for example values of 0.888, 0.155, 0.213, 0.264, 0.304 and 0.331 for gears sold by Takeuchi Gear Works, Ltd. To obtain gears having degrees of oblateness .epsilon. outside those commercially available requires special manufacture at a resulting high cost. Consequently the cost of a machine that may deposit predetermined amounts of lining material in cap shells and which is to be able to accommodate cap shells of varying depths may be unduly expensive if non-circular gears are required that are not commercially available.
From a non-circular gear manufacturing standpoint, it is difficult to form the teeth of gears coming within certain degrees of oblateness, particularly in excess of 0.331. This limitation presents a limit of the degree of speed conversion that may be obtained from a set of non-circular gear pairs.
It is therefore an object of my invention to provide for an apparatus for distributing lining material in cap shells having varying depths where the degree of rotational speed of the cutting knife utilized to cut a predetermined amount of lining material extruded from an extrusion passage and to deposit the same onto a predetermined area of the bottom of a shell may be easily and accurately varied and without involving change of expensive gear sets.